Simulation techniques thermodynamic perturbation

The ability to evaluate free energies is among the most important features of molecular simulations, and finds application in a wide variety of chemical and biochemical systems. This article reviewed two of the more commonly used techniques, thermodynamic perturbation and thermodynamic integration. More extensive reviews of these and other techniques, " as well as a compendium of molecular modeling software which includes codes for free energy evaluation, are available. 

Because of the long-range and reduced symmetry of the dipole-dipole interaction, analytical methods such as the thermodynamic perturbation theory presented in Section II.B.l. will be applicable only for weak interaction. Numerical simulation techniques are therefore indispensable for the study of interacting nanoparticle systems, beyond the weak coupling regime. 

This chapter has reviewed theoretical and practical aspects of thermodynamic perturbation and thermodynamic integration, two popular methods of extracting free energies from molecular simulations. These methods find broad application in molecular simulation studies of chemical and biochemical systems. The fundamental importance of free energy in physical and chemical processes will inspire further development and refinement of these techniques. With the increasing performance of new computer architectures,these free energy techniques will become even more powerful and versatile tools. 

This article describes thermodynamic perturbation and thermodynamic integration. These methods form the basis of the most popular computational techniques for free energy difference evaluation with molecular simulations. 

Straatsma, T. P. (1987). Free energy evaluation by molecular dynamics simulations. Analysis of the perturbation method and a thermodynamic integration technique. In Department of Biophysical ChemistryUniversity of... 

Historically, the basis of gas permeation module design was first proposed by Weller and Steiner in 1950. Nowadays, modem computation techniques provide numerical solutions to the problems thanks to dedicated routines. Orthogonal collocation methods or perturbation methods " are reported to be particularly attractive when a minimum resolution time and computational efforts are required. Several of these routines have been implemented in commercial process simulation software, where advantage can be taken of thermodynamics or unit operation design packages in order to simulate hybrid or multi-stage operations with gas separation membranes. Nevertheless, much effort has been devoted to... 

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